For treatment of progressive vascular lesions such as port wine stain (PWS) birthmarks, there is a need for innovative, personalized methods to maximize the reduction in PWS redness per treatment session. Our long-term goal is to develop appropriate methods to mitigate the physical and psychosocial trauma associated with PWS birthmarks. The objective of this application is to quantify the reduction in redness and degree of safety associated with immediate blood flow image-guided retreatment of PWS skin. The central hypothesis is that immediate image-guided retreatment will result in a larger average reduction in redness than the redness reduction without immediate retreatment. Once the proposed research has been completed, we expect to possess sufficient data that demonstrate in a compelling fashion the need for an objective, image-guided approach to improve significantly the reduction in redness associated with each treatment session. Due to the potentially low cost and feasible miniaturization of the imaging technology, a quantitative demonstration of improved treatment efficacy with real-time blood-flow visualization is expected to impact surgical practice in a wide range of disciplines. We will respond to the following specific aims: 1) Establish the quantitative criteria used to identify regions of persistent perfusion in the blood flow maps;and 2) identify the impact of image-guided laser surgery on the quantitative reduction in PWS skin redness. Our contribution here is expected to be development of an instrument capable of providing intraoperative feedback to the clinician and determination of the impact of immediate retreatment of regions of persistent post-treatment perfusion on overall laser PWS therapeutic efficacy, which would ultimately reduce the number of patient visits required to achieve complete PWS removal. PUBLIC HEALTH RELEVANCE: The proposed studies are expected to result in validation of a real-time blood flow imaging method for intraoperative surgical guidance. This method has potential applicability in other clinical disciplines, including dermatology (i.e., peripheral vascular disorders, melanoma mapping), neurosurgery (i.e., image-guided tumor resection), and ophthalmology (i.e., retinal surgery).